In this work, an ether-bridged aromatic carboxylic acid, 2-(2-carboxyphenoxy)terephthalic acid (H3cpta), was applied as an unexplored building block for the generation of a novel series of coordination compounds, which represent the first examples of structurally characterized products derived from H3cpta, thus opening up its use as a versatile building block in crystal engineering research. The obtained products were formulated as [Cd(μ-Hcpta)(phen)(H2O)]n (1), [Mn(μ-Hcpta)(phen)(H2O)]n (2), {[Cd3(μ3-Hcpta)(μ4-cpta)(μ-Cl)(H2O)4]·2H2O}n (3), {[Cd3(μ6-cpta)2(py)2]·5H2O}n (4), [Mn3(μ5-cpta)2(2,2′-bipy)2]n (5), [Mn3(μ4-cpta)2(phen)3(H2O)2]n (6), {[Zn3(μ3-cpta)2(phen)3]·3H2O} (7), [Cd2(μ4-cpta)(μ-Cl)(phen)2]n (8), [Cd3(μ5-cpta)2(phen)2(H2O)2]n (9), [Cd3(μ4-cpta)2(phen)3(H2O)2]n (10), [Cd3(μ5-cpta)2(H2biim)2]n (11), [Zn2(μ6-cpta)(μ-Hbiim)]n (12), and [Ni3(μ3-cpta)2(phen)3(py)3(H2O)3]n (13). These compounds were assembled in the presence of an optional N-donor ancillary ligand, which was selected from 1,10-phenanthroline (phen), pyridine (py), 2,2′-bipyridine (2,2′-bipy), or 2,2′-biimidazole (H2biim). The obtained compounds 1–13 were fully characterized, including by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), powder (PXRD) and single-crystal X-ray diffraction. The structures of 1–13 vary from a discrete 0D dimer (1) to the 1D (2, 3, 7, and 13) and 2D (5, 6, and 8–11) coordination polymers, as well as to the 3D metal–organic frameworks (MOFs 4 and 12). Such a wide structural diversity of 1–13 is guided by the following factors: a type of metal(II) node and counter anion, a deprotonation degree of the principal H3cpta block, and/or a type of an auxiliary ligand. Topological classification of H-bonded (in 1) and metal–organic (in 2–13) underlying networks was performed, disclosing the following topological types: sql (in 1), 2C1 (in 2 and 7), 3,4,5L45 (in 5, 9, and 11), 3,4L128 (in 6 and 10), 3,3,4L29 (in 8), and SP 1-periodic net (in 13), as well as some topologically unique nets (in 3, 4, and 12). Besides, magnetic properties of 2, 5, 6, and 13 were studied and modeled, revealing antiferromagnetic interactions between adjacent metal(II) centers. In addition, luminescence properties were investigated for 1, 3, 4, and 7–12; MOF 4 can be used as a sensitive material for the detection of Fe3+ ions in aqueous solution through the luminescence quenching effect.

In this work, a trifunctional N,O-building block, 5-(4-carboxyphenoxy)nicotinic acid (H2cpna), that combines three distinct types of functional groups (COOH, N-pyridyl, and O-ether) was used for the hydrothermal assembly of thirteen new coordination compounds: [Co(μ3-Hcpna)2]n (1), [Mn(μ4-cpna)(H2O)]n (2), [Mn(μ4-cpna)(H2O)2]n (3), [Mn(μ-cpna)(2,2′-bipy)(H2O)2]n (4), {[Ni(μ3-cpna)(2,2′-bipy)(H2O)]2·H2O}n (5), {[Cd(μ3-cpna)(2,2′-bipy)]·2H2O}n (6), [Zn2(μ-cpna)2(2,2′-bipy)2] (7), [Cu(μ-cpna)(2,2′-bipy)(H2O)]n (8), {[Mn(μ-cpna)(phen)2]·6H2O}n (9), {[Ni(μ3-cpna)(phen)(H2O)]·H2O}n (10), [Zn2(μ-cpna)2(phen)2] (11), {[Pb(μ3-cpna)(phen)]·H2O}n (12), and [Ni(μ3-cpna)(4,4′-bipy)0.5(H2O)]n (13). These products were synthesized from the corresponding metal(II) chlorides, H2cpna, NaOH, and optional N-donor supporting ligands or templates {bis(4-pyridyl)amine (bpa), 2,2′-bipyridine (2,2′-bipy), 4,4′-bipyridine (4,4′-bipy), or 1,10-phenanthroline (phen)}. Products 1–13 were characterized in the solid state by standard methods, including elemental and thermogravimetric analysis (TGA), IR spectroscopy, and powder (PXRD) and single-crystal X-ray diffraction. The structures of 1–13 feature distinct structural types, namely the 3D metal–organic frameworks (MOFs 1–3), the 2D coordination polymers (5, 6, 10, 12, and 13), the 1D coordination polymers (4, 8, and 9), and the 0D discrete cyclic dimers (7 and 11). Such a wide structural diversity of 1–13 is driven by various factors, including the type of the metal(II) node, the deprotonation degree of H2cpna, and/or the type of supporting ligand or template. Notably, an addition of bpa can tune the structure of MOF 3 by the template effect. Topological classification of underlying metal–organic networks was performed, leading to several distinct topological nets: rtl (in 1), hxg-d-4-C2/m (in 2), sra (in 3), 2C1 (in 4, 8 and 9), fes (in 5, 10, and 12), hcb (in 6), and 3,4L83 (in 13). The magnetic behavior of 1–5, 8–10, and 13 was studied and theoretically modeled, disclosing antiferromagnetic interactions. The luminescence behavior of 6, 7, 11, and 12 was also investigated.

•New series of metal-organic and supramolecular 3D frameworks was synthesized.•The obtained compounds were fully characterized and their structures were established.•Biphenyl-2,5,3′-tricarboxylic acid acts as a flexible and versatile building block.•Topological analysis and classification of the 3D frameworks was carried out.•Magnetic and luminescent properties of obtained products were investigated and discussed.Biphenyl-2,5,3′-tricarboxylic acid (H3L) was selected as an unexplored tricarboxylate building block and applied for the hydrothermal synthesis of three novel coordination compounds, namely a 0D tetramer [Co4(HL)2(μ3-HL)2(phen)6(H2O)2]·3H2O (1) and two 3D metal-organic frameworks (MOFs) [Cd3(μ5-L)(μ6-L)(py)(μ-H2O)2(H2O)]n·H2O (2) and [Zn3(μ4-L)2(2,2′-bpy)(μ-4,4′-bpy)]n·2H2O (3). These products were easily generated in aqueous medium from the corresponding metal(II) chlorides, H3L, and various N-donor ancillary ligands, selected from 1,10-phenanthroline (phen), pyridine (py), 2,2′-bipyridine (2,2′-bpy), and 4,4′-bipyridine (4,4′-bpy). Compounds 1–3 were isolated as stable crystalline solids and were fully characterized by IR and UV–vis spectroscopy, elemental, thermogravimetric (TGA), powder (PXRD) and single-crystal X-ray diffraction analyses. Compound 1 possesses a discrete tetracobalt(II) structure, which is extended into a 3D H-bonded network with the pcu topology. In contrast, MOF 2 discloses a very complex trinodal 4,5,12-connected net with an undocumented topology, while MOF 3 features the nce/I topological framework. The magnetic (for 1) and luminescence (for 2 and 3) properties were also studied and discussed. The present study thus widens a still very limited family of metal-organic and supramolecular frameworks driven by flexible biphenyl-2,5,3′-tricarboxylate building blocks.

A new series of eight lanthanide coordination compounds, namely [Ln(5-Fnic)3(H2O)3]2·2H2O (Ln = La (1), Pr (2), Nd (3), Eu (4), Gd (5), and Tb (6)), [Tm(5-Fnic)2(H2O)4]2[5-Fnic]2·2H2O (7), and [Eu(5-Fnic)2(phen)2(NO3)(H2O)]·2H2O (8) were generated by a hydrothermal self-assembly method in H2O from the corresponding lanthanide metal(III) nitrates, with 5-fluoronicotinic acid (5-FnicH) as the main building block, and an optional (for 8) 1,10-phenanthroline (phen) as an ancillary ligand. All the products (1–8) were fully characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, and powder and single-crystal X-ray diffraction analyses. Compounds 1–6 are isostructural and reveal neutral dilanthanide(III) molecular units, 7 is ionic and has a cationic Tm2 core, whereas 8 displays a mononuclear structure. Distinct crystal packing patterns driven by strong intermolecular hydrogen bonds were observed in 1–6, 7, and 8, resulting in the 0D → 3D (1–7) or 0D → 1D (8) extension of the structures into H-bonded networks; their topological analysis and classification were performed. Products 1 and 3–8 constitute the first La, Nd, Eu, Gd, Tb, and Tm coordination compounds derived from 5-fluoronicotinic acid. The magnetic properties of compounds 2, 3, 5, and 7 were investigated. Besides, products 4, 6, and 8 exhibit a reversible temperature-induced dehydration/hydration behavior, which also influences their solid state luminescence properties that were studied in detail. The intensity of the emission bands of the dehydrated samples greatly increases after thermal removal of water molecules and then returns back to the original level upon exposure to water. This reversible behavior is more pronounced in 8 given the additional presence of phenanthroline moieties.

5-(6-Carboxypyridin-3-yl)isophthalic acid (H3L) was utilized as an almost unexplored multifunctional ligand to construct, under hydrothermal conditions, ten new coordination compounds, namely, [Cd(μ2-H2L)2]n (1), [Ni(HL)(H2biim)2] (2), [Mn(μ2-HL) (phen)(H2O)]2·2H2O (3), {[Mn3(μ4-L)2(H2O)6]·3H2O}n (4), {[Co3(μ5-L)2(H2O)6]·2H2O}n (5), {[Ni3(μ4-L)2(H2O)6]·2H2O}n (6), {[Zn3(μ5-L)2(H2O)4]·2H2O}n (7), {[Mn3(μ5-L)2(H2O)6]·4H2O}n (8), {[Co3(μ4-L)2(μ2-4,4′-bipy)(H2O)6]·2H2O}n (9), and {[Ni3(μ5-L)2(H2O)6]·2H2O}n (10), also using an optional auxiliary ligand selected from 2,2′-biimidazole (H2biim), 1,10-phenanthroline (phen), or 4,4′-bipyridine (4,4′-bipy). The obtained compounds 1–10 were analyzed by IR spectroscopy, thermogravimetric and elemental analysis, and single-crystal and powder X-ray diffraction. The structures of the products vary from 3D MOFs (metal–organic frameworks 5 and 7–10) to 2D CPs (coordination polymers 1, 4, and 6) as well as to a discrete 0D monomer 2 and a dimer 3. The latter two are extended by multiple hydrogen bonds into complex 3D supramolecular networks. This structural difference in 1–10 is directed by the kind of metal(II) center, the deprotonation degree of the principal H3L building block, and/or the kind of auxiliary ligand. Notably, an addition of 4,4′-bipy can tune the structures of MOFs 8–10 by the coordination or template effect. Topological classification of metal–organic and H-bonded underlying networks was performed, disclosing a variety of topological nets: sql (in 1), 3,10T3 (in 3), 3,4L83 (in 4 and 6), tcs (in 5, 8, and 10), 3,4,5T95 (in 7), and sra (in 9), as well as a topologically unique network in 2. The magnetic properties (for compounds 3–6, 8–10) and luminescent properties (for compounds 1, 7) were also investigated and discussed. In fact, compound 7 exhibits an intense violet emission in the solid state. Measurements of the magnetic susceptibility indicate interactions of an antiferromagnetic nature between the adjacent metal(II) centers in the compounds 3–6 and 8–10. The obtained products represent the first series of metal–organic compounds assembled from the H3L precursor, thus opening up its application as a new pyridine–tricarboxylate organic block for designing CPs or MOFs.

Four new crystalline solids, namely [Co2(µ2-5-Clnic)2(µ3-5-Clnic)2(µ2-H2O)]n (1), [Co(5-Clnic)2(H2O)4]·2(5-ClnicH) (2), [Pb(µ2-5-Clnic)2(phen)]n (3), and [Cd(5-Clnic)2(phen)2]·3H2O (4) were generated by hydrothermal self-assembly methods from the corresponding metal(II) chlorides, 5-chloronicotinic acid (5-ClnicH) as a principal building block, and 1,10-phenanthroline (phen) as an ancillary ligand (optional). All the products 1–4 were characterized by IR spectroscopy, elemental analysis, thermogravimetric (TGA), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Their structures range from an intricate 3D metal-organic network 1 with the 3,6T7 topology to a ladder-like 1D coordination polymer 3 with the 2C1 topology, whereas compounds 2 and 4 are the discrete 0D monomers. The structures of 2 and 4 are further extended (0D→2D or 0D→3D) by hydrogen bonds, generating supramolecular networks with the 3,8L18 and ins topologies, respectively. Synthetic aspects, structural features, thermal stability, magnetic (for 1) and luminescent (for 3 and 4) properties were also investigated and discussed.A new series of crystalline solids was self-assembled and fully characterized; their structural, topological, luminescent and magnetic features were investigated.

Two compounds, namely a 2D coordination polymer {[Ni(µ3-bpdc)(H2O)]·H2O}n (1) and a 3D metal–organic framework (MOF) [Mn(µ4-bpdc)(phen)]n (2), were generated by a hydrothermal self-assembly from the corresponding metal(II) chlorides, 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpdc) as a main building block, and an optional ancillary 1,10-phenanthroline (phen) ligand. The obtained products were characterized by IR spectroscopy, elemental, thermogravimetric, powder and single-crystal X-ray diffraction analyses. Compound 1 possesses a 2D double-layered network with the plane SP KIa topology defined by the point symbol of (82.10), which is further extended into a 3D supramolecular architecture via hydrogen bonds. MOF 2 features a 3D net with the pts topology and point symbol of (42.84). The magnetic properties for both compounds were also investigated, indicating antiferromagnetic interactions between the adjacent metal ions.

Five new coordination compounds, namely [Ni(5-Fnic)2(μ2-H2O)0.5]n (1), [Co(5-Fnic)2(H2biim)]n (2), {[Cd(5-Fnic)2(phen)]·2H2O}n (3), [Cd(5-Fnic)2(H2biim)2] (4), and [Co(5-Fnic)2(H2O)4] (5), were generated by hydrothermal methods from the metal(II) nitrates, 5-fluoronicotinic acid (5-FnicH), and an optional ancillary 1,10-phenanthroline (phen) or 2,2′-biimidazole (H2biim) ligand. All the products 1–5 were characterized by IR spectroscopy, elemental, thermogravimetric, and single-crystal X-ray diffraction analyses. Their structures range from the intricate 3D metal–organic framework (MOF) 1 to the 1D coordination polymers 2 and 3, and the discrete 0D monomers 4 and 5. The structures of 2–5 are further extended [1D → 2D (2), 1D → 1D (3), 0D → 1D (4), and 0D → 3D (5)] into various H-bonded networks. The topological analysis of the underlying coordination (in 1) and H-bonded (in 2–5) nets revealed a very rare 3,6T10 MOF topology in 1, a parallel 2D + 2D interpenetration of the sql nets in 2, a topologically unique double chain in 3, a simple 2C1 topology in 4, and a pcu (alpha-Po primitive cubic) topology in 5. The magnetic (for 1 and 2) and luminescent (for 3 and 4) properties were also investigated and discussed.

A novel flexible multifunctional building block (H3L) bearing picolinate and terephthalate functionalities was designed and applied for the hydrothermal self-assembly generation of a series of coordination compounds [Co(H2L)2(H2O)2] (1), [M(HL)(H2O)]n {M = Cd (2) and Mn (3)}, {[Mn1.5(L)(phen)(H2O)2]·H2O}n (4), [Zn3(L)2(H2O)6]n (5), and {[Zn3(L)2(py) (H2O)4]·4H2O}n (6) {wherein H3L = 2-(4-carboxypyridin-3-yl)-terephthalic acid, phen = 1,10-phenanthroline, py = pyridine}. All the obtained products 1–6 were fully characterized by IR spectroscopy, elemental, thermogravimetric, powder and single-crystal X-ray diffraction analyses. By adjusting the molar ratio of NaOH and H3L ligand, the latter becomes partially deprotonated to form the H2L− blocks in 1 and HL2− moieties in 2 and 3, or completely deprotonated to create the L3− units in 4–6. The structures of the obtained compounds range from a discrete 0D monomer 1 and 1D coordination polymers 4 and 5 to 2D coordination polymers 2 and 3, and an intricate 3D metal–organic framework 6; their detailed topological classification was also performed. The structures of 1–5 are further extended [0D → 3D (1), 1D → 3D (4, 5), and 2D → 3D (2, 3)] into supramolecular networks by means of multiple hydrogen bonds. The results reveal that the nature of metal(II) ion, molar ratio between NaOH and H3L ligand, and the presence (optional) of auxiliary ligand play a significant role in determining dimensionality, topology and other structural features of the obtained products. Magnetic susceptibility measurements indicate that compounds 3 and 4 have dominating antiferromagnetic couplings between metal centers. Furthermore, luminescent properties of 2, 5, and 6 were also investigated.

A series of novel mixed-ligand coordination polymers, namely, {[Cd2(μ4-L)(μ3-OH)(phen)2]·2H2O}n (1), {[Mn3(μ5-L)2(phen)2(H2O)]·H2O}n (2), [Cd2(μ3-L)(H2biim)2(μ2-Hbiim)]n (3), {[Pb2(μ4-L)(μ4-bpdc)0.5(phen)2]·H2O}n (4), [Cd2(μ5-L)(μ2-bpdc)0.5(phen)2]n (5), and [Zn2(μ4-L)(μ2-bpdc)0.5(py)2]n (6), was hydrothermally synthesized using 4-(5-carboxypyridin-2-yl)isophthalic acid (H3L) as a new and virtually unexplored multifunctional pyridine-tricarboxylate building block, along with various auxiliary ligands {phen = 1,10-phenanthroline, H2biim = 2,2′-biimidazole, H2bpdc = 4,4′-biphenyldicarboxylic acid, and py = pyridine}. All the products 1–6 were characterized by IR spectroscopy, elemental, thermogravimetric, and single-crystal X-ray diffraction analyses. Compounds 1, 3, and 5 reveal 2D metal–organic layers with the kgd, fes, and 3,4,5L5 topology, respectively, whereas the metal–organic frameworks (MOFs) 2, 4, and 6 disclose 3D underlying nets with the unique (2, 4) or ins (6) topology. The results indicate that the nature of the metal(II) ion and type of auxiliary ligand play a significant role in determining the dimensionality, topology and other structural features of the obtained products. Luminescent (for 1 and 3–6) and magnetic (for 2) properties were studied and discussed.

•Two dicarboxylate-driven 3D Cd(II) and 0D Mn(II) compounds were synthesized.•Cd(II) MOF is a 4-fold interpenetrated dia topological net.•Mn(II) complex forms H-bonded ladder with SP 1-periodic net (4,4)(0,2) topology.•Luminescent and magnetic properties were investigated and discussed.Two new coordination compounds, namely a 3D metal–organic framework (MOF) {[Cd2(L)2(phen)2]·H2O}n (1) and a discrete 0D dimer [Mn(L)0.5(HL)(phen)2]2·2H2O (2), were generated by a hydrothermal method from the metal(II) chlorides, 4,4′-(pyridine-2,5-diyl)dibenzoic acid (H2L) as a main building block, and an ancillary 1,10-phenanthroline (phen) ligand. The products 1 and 2 were characterized by IR spectroscopy, elemental, thermogravimetric, and single-crystal X-ray diffraction analyses. Compound 1 possesses an intricate 3D metal–organic framework based on tetracadmium(II) double-helicate units which, after simplification, resulted in a 4-fold interpenetrated underlying net with the dia topology. Compound 2 features a dimeric molecular structure, which is extended (0D → 1D) by hydrogen bonds into a 1D double chain network. It was topologically classified as a simple 3-connected ladder with the SP 1-periodic net (4,4)(0,2) topology. The luminescent (for 1) and magnetic (for 2) properties were also investigated and discussed.Two new coordination compounds driven by 4,4′-(pyridine-2,5-diyl)dibenzoic acid were generated and structurally characterized; one of the products is a 3D MOF with a 4-fold interpenetrated dia topological network.

Twelve lanthanide coordination polymers associated with the organic ligand 5-(2′-carboxylphenyl) nicotinic acid (H2cpna): {[Ln(Hcpna)(cpna)(phen)]·H2O}n (Ln = Sm (1), Tb (2), Ho (3), phen = 1,10-phenanthroline), {[Sm(Hcpna)(cpna)(phen)]·2H2O}n (4), {[Ln2(cpna)3(H2O)3]·4H2O}n (Ln = Y (5), Tb(6), Dy (7), Ho (8)), [Lu2(cpna)3(H2O)2]n (9), {[Y2(cpna)3(phen)2(H2O)]·H2O}n (10), and [Ln(cpna)(phen)(NO3)]n (Ln = Tm (11), Lu (12)) have been prepared by hydrothermal methods and structurally characterized. The structure analyses reveal that complexes 1–3 are isostructural and possess unique three-dimensional (3D) frameworks based on the dodecanuclear Sm/Tb/Ho macrocycles. Complex 4 exhibits a one-dimensional (1D) wheel-chain structure, which further builds three-dimensional (3D) supramolecular architecture via O–H⋯N hydrogen-bonding interactions. Complexes 5–8 are also isostructural and display three-dimensional (3D) open frameworks, which possess two types of channels along the a- and b-axis, respectively. Complexes 9 and 10 feature three-dimensional (3D) frameworks and are created from tetranuclear and dinuclear units, respectively. Complexes 11 and 12 are isostructural and demonstrate one-dimensional (1D) double chain structures, which further build three-dimensional (3D) supramolecular architecture via C–H⋯O hydrogen-bonding. The results show that the pH value of the reaction system, anion, auxiliary ligand and lanthanide contraction play a significant role in determining the structures of the complexes. In addition, the results of luminescent measurements for compounds 2 and 6 in the solid state at room temperature indicate that the different types of structures have a dissimilar influence on their characteristic luminescence. The magnetic properties of compounds 1, 3, 4, 7 and 11 have been investigated. Furthermore, thermal stabilities for 1–12 and the dehydration/hydration properties of compound 6 have also been studied.

Eight new coordination polymers [Mn(H2btc)2(4,4′-bpy)2]n (1), {[Cd(Hbtc)(phen)(H2O)]·H2O}n (2), [Pb(Hbtc)(phen)]n (3), {[Cd3(btc)2(H2O)5]·4H2O}n (4), {[Cd3(btc)2(phen)2(H2O)]·H2O}n (5), [Mn3(btc)2(2,2′-bpy)2]n (6), {[Ni3(btc)2(4,4′-bpy)2.5(μ2-H2O)(H2O)3]·3H2O}n (7), and {[Co2(btc)(μ3-OH)(μ2-H2O) (8), were assembled from different metal(II) chlorides and biphenyl-2,4,4′-tricarboxylic acid (H3btc) as a main building block, and various aromatic N-donors (phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine) as supporting ligands. By adjusting the reaction pH, H3btc undergoes a partial deprotonation to give the H2btc− form in 1, and the Hbtc2− moiety in 2 and 3, and the fully deprotonated btc3− form in 4–8. All the products were fully characterized by single crystal X-ray diffraction analysis. Compounds 1 and 2 possess the double helical chain and wheel chain 1D coordination networks, respectively, which are further extended into the 3D supramolecular architectures via hydrogen bonds. The 2D and 3D metal–organic networks of 6 and 3 were topologically classified, revealing the trinodal 3,6,6-connected and uninodal 4-connected nets with the 3,6,6L3 and sra topologies, respectively. Compounds 4, 5, 7, and 8 feature the very complex 3D metal–organic framework structures, generating either pentanodal 3,4,5,6,6- (4), 3,3,4,5,5- (5), and 4,4,4,5,6-connected (7), or tetranodal 3,5,6,6-connected (8) underlying nets with the hitherto undocumented topologies. The obtained data revealed that different coordination modes of the H2btc−/Hbtc2−/btc3− ligands and the resulting crystal architectures depend on a variety of factors, such as the solution pH and the nature of metal ions and N-donor auxiliary ligands. Magnetic susceptibility measurements indicate that 1 and 8 show a dominating ferromagnetic coupling, while 6 and 7 exhibit an antiferromagnetic coupling between the metal centers. Furthermore, thermal stability of 1–8 and luminescent properties of 2–5 were also studied and discussed.

A ligand 5-(2′-carboxylphenyl) nicotic acid (H2cpna) has been successfully applied to construct a series of coordination complexes {[Cd(Hcpna)2(H2O)2]·3H2O}n (1), [Cd(cpna)(H2O)]n (2), [M(cpna)(2,2′-bipy)(H2O)]n (M = Cd (3), Co (4), and Mn (5)), [Co(cpna)(phen)(H2O)]n (6), [Mn(cpna)(phen)(H2O)]n (7), {[Nd(Hcpna)(cpna)(H2O)2]·3H2O}n (8), and {[Ln(Hcpna)(cpna)(phen)]·2H2O}n (Ln = Pr (9), Nd (10), Eu (11), and Gd (12), 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline) under hydrothermal conditions. By adjusting the reaction pH, H2cpna ligand is partially deprotonated to form Hcpna– in 1 and completely deprotonated to create cpna2– in 2–7, and both forms are observed in 8–12. Complexes 1–5 and 8 possess two-dimensional (2D) layered structures, which are further extended into 3D metal–organic supramolecular frameworks by C–H···O hydrogen bond and/or π–π stacking interactions. Complexes 6, 7, and 9–12 exhibit one-dimensional (1D) chain structures, which further build three-dimensional (3D) supramolecular architecture via C–H···O hydrogen-bonding and/or π–π stacking interactions. The results revealed that the pH value of the reaction system and auxiliary ligand play an important role in determining the structures of the complexes. Magnetic susceptibility measurements indicate that compounds 4–10 and 12 have dominating antiferromagnetic couplings between metal centers. Furthermore, thermal stabilities for 1–12 and luminescent properties for 1–3, and 11 are also discussed in detail.

A new heterocyclic carboxylate ligand, 5-(4′-pyridyl)-3-methyl-benzoic acid (Hpmba), was synthesized to construct a Mn(II) coordination polymer, namely [Mn(pmba)2]n (1). Complex 1 crystallizes in monoclinic space group C2/c, with a = 17.44(2), b = 17.040(12), c = 8.680(15) Å, β = 111.258(13), V = 2404(5) Å3, and Z = 4. Single-crystal X-ray diffraction studies show that complex 1 has a 3D metal-organic supramolecular framework consisting of double helical chains. Magnetic studies for complex 1 show antiferromagnetic coupling between the nearest Mn(II) ions, with g = 2.11 and J = −10.1 cm−1.

Two lanthanide(III) coordination polymers, namely [Ce(pzdc)1.5(H2O)]n (1), [Er(pzdc)(μ2-OH)(H2O)]n·nH2O (2) (H2pzdc = pyrazine-2,5-dicarboxylic acid), have been hydrothermally synthesized and characterized by single crystal X-ray diffraction and magnetic measurements. Polymer 1 crystallizes in triclinic space group P-1, with a = 6.2875(6), b = 6.7396(6), c = 13.3858(14) Å, α = 82.858(4), β = 83.118(4), γ = 63.452(4)°, V = 502.16(8) Å3, and Z = 2. Polymer 2 crystallizes in monoclinic space group P2(1)/c, with a = 11.706(4), b = 6.151(2), c = 14.063(5) Å, β = 92.255(3), V = 502.16(8) Å3, and Z = 4. Single-crystal X-ray diffraction studies show that compound 1 possess a 3D framework structure consisted of double chains. Compound 2 features a 3D open framework structure with a dinuclear Er(III) secondary building unit. Magnetic studies for complex 1 show stronger antiferromagnetic coupling between the Ce(III) ions.

Four coordination polymers, [Zn(pda)(bpy)(H2O)]n·nH2O (1), [Cd(pda)(prz)(H2O)]n (2), [Co3(μ3-OH)2(pda)2(pyz)]n·2nH2O (3) and [Pr2(pda)3(H2O)2]n (4) (H2pda=1,3-phenylendiacetic acid, bpy=4,4′-bipyridine, prz=piperazine and pyz=pyrazine) have been hydrothermally synthesized and characterized. Complex 1 is a 1D wheel-like chain structure, which is further extended into a 3D metal-organic supramolecular framework by H-bonds and π–π stacking interactions. Complex 2 is a 1D ladder-like chain structure, which is also further extended into a 3D metal-organic supramolecular framework by H-bonds. Complex 3 possess a 2D sheet structure with infrequent two pairs of double-helix chains. Complex 4 features a 3D structure. Both 1 and 2 display strong blue fluorescent emission at room temperature. Magnetic susceptibility measurements of complexes 3 and 4 exhibit antiferromagnetic interactions between the nearest metal ions, with C=9.99 and 3.43 cm3 mol−1 K, and θ=−23.9 and −46.3 K, respectively.Graphical abstractFour new coordination polymers with 1,3-phenylenediacetate ligands have been hydrothermally synthesized and characterized.Complexes 1 and 2 display strong blue fluorescent emission at room temperature. Magnetic susceptibility measurements of 3 and 4 exhibit antiferromagnetic interactions between the nearest metal centers.Research highlights► Coordinative property of H2pda ligand was shown when bonded by different block metals. ► Careful selection of co-ligand and metals resulted in dramatic framework evolution. ► (c) The compounds constructed with Zn2+ and Cd2+ exhibit strong blue fluorescent emission. ► The magneto-structural correlation of the complexes constructed with Co2+ and Pr3+ was elucidated.

Three Co(II) and Ni(II) complexes, namely [Co(bpdc)(H2O)2] (1), [Ni(bpdc)(H2O)2] (2), and [Co2(bpdc)2(prz)0.5(H2O)3]·0.5H2O (3) (H2bpdc = 2,2′-bipyridine-6,6′-dicarboxylic acid and prz = piperazine), have been synthesized from H2bpdc and the corresponding metal salts under hydrothermal conditions. The complexes were characterized by physico-chemical and spectroscopic methods, as well as by X-ray crystallography. Compounds 1 and 2 both consist of neutral mononuclear molecules, of [Co(bpdc)(H2O)2] and [Ni(bpdc)(H2O)2], respectively. Compound 3 consists of a mononuclear molecule of [Co(bpdc)(H2O)2] and a binuclear molecule of [Co2(bpdc)2prz (H2O)2]. The discrete neutral complexes 1–3 further extend their structures into three-dimensional supramolecular architectures by intermolecular O–H⋯O and C–H⋯O hydrogen bonds as well as π–π stacking interactions. Magnetic susceptibility measurements show that complex 3 exhibits weak ferromagnetic interactions between the two Co(II) ions bridged by the prz ligand, with C = 5.41 cm3 mol−1 K and θ = +27.6 K, respectively.

Two coordination polymers, namely [M(cpna)(phen)(H2O)]n (M = Ni, 1; Cd, 2, H2cpna = 5-(2′-carboxylphenyl) nicotic acid, phen = 1,10-phenanthroline), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, magnetic and luminescence measurements. Single-crystal X-ray diffraction studies show that the two complexes are isostructural polymers. They have 1D step-like chain structures, which are further extended into 3D metal–organic supramolecular frameworks by π–π stacking interactions. Magnetic studies for complex 1 show antiferromagnetic coupling between the adjacent Ni(II) centers, with g = 2.10 and J = −4.30 cm−1. Complex 2 displays strong green fluorescent emission at room temperature.

Two Mn(II) coordination polymers, namely [Mn(bpda)]n (1) and [Mn(bpda)(bpy)0.5]n (2) (H2bpda = 1,1′-biphenyl-3,3′-dicarboxylic acid and bpy = 4,4′-bipyridine), have been synthesized from H2bpdc, bpy, and MnSO4·2H2O under hydrothermal conditions. The complexes were characterized by physicochemical and spectroscopic methods, as well as by X-ray crystallography. Compound 1 possesses a 3D structure consisting of carboxylate-bridged edge-sharing Mn–O–Mn double chains. Compound 2 features a 3D open structure with a dinuclear Mn(II) secondary building unit. Magnetic susceptibility measurements of compounds 1 and 2 exhibit antiferromagnetic interactions between the nearest Mn(II), with J = –11.3 cm−1 and g = 2.12 for 1, and J = –13.5 cm−1 and g = 2.12 for 2.

Twelve lanthanide coordination polymers associated with the organic ligand 5-(2′-carboxylphenyl) nicotinic acid (H2cpna): {[Ln(Hcpna)(cpna)(phen)]·H2O}n (Ln = Sm (1), Tb (2), Ho (3), phen = 1,10-phenanthroline), {[Sm(Hcpna)(cpna)(phen)]·2H2O}n (4), {[Ln2(cpna)3(H2O)3]·4H2O}n (Ln = Y (5), Tb(6), Dy (7), Ho (8)), [Lu2(cpna)3(H2O)2]n (9), {[Y2(cpna)3(phen)2(H2O)]·H2O}n (10), and [Ln(cpna)(phen)(NO3)]n (Ln = Tm (11), Lu (12)) have been prepared by hydrothermal methods and structurally characterized. The structure analyses reveal that complexes 1–3 are isostructural and possess unique three-dimensional (3D) frameworks based on the dodecanuclear Sm/Tb/Ho macrocycles. Complex 4 exhibits a one-dimensional (1D) wheel-chain structure, which further builds three-dimensional (3D) supramolecular architecture via O–H⋯N hydrogen-bonding interactions. Complexes 5–8 are also isostructural and display three-dimensional (3D) open frameworks, which possess two types of channels along the a- and b-axis, respectively. Complexes 9 and 10 feature three-dimensional (3D) frameworks and are created from tetranuclear and dinuclear units, respectively. Complexes 11 and 12 are isostructural and demonstrate one-dimensional (1D) double chain structures, which further build three-dimensional (3D) supramolecular architecture via C–H⋯O hydrogen-bonding. The results show that the pH value of the reaction system, anion, auxiliary ligand and lanthanide contraction play a significant role in determining the structures of the complexes. In addition, the results of luminescent measurements for compounds 2 and 6 in the solid state at room temperature indicate that the different types of structures have a dissimilar influence on their characteristic luminescence. The magnetic properties of compounds 1, 3, 4, 7 and 11 have been investigated. Furthermore, thermal stabilities for 1–12 and the dehydration/hydration properties of compound 6 have also been studied.